'balneum' originates from Latin, specifically the Latin word 'balneum', ultimately borrowed from Greek 'balaneion' where the element 'balane-' meant 'bath'.

'balneum' changed from Greek 'balaneion' into Latin 'balneum' and was later borrowed into English (typically in learned or technical contexts) as 'balneum'.

Initially it meant 'bath' in a general sense; over time the meaning has remained 'bath' but narrowed in English to archaic or specialized uses (e.g., archaeological descriptions or medical balneotherapy).